There are various characteristics of canola growth and development that make harvest challenging. Pod drop, pod shattering, lodging and late and/or uneven maturity can reduce yield and profit potential. Plant breeding for improved traits has helped reduce risk and provided harvest flexibility to canola growers. With these improvements, canola product selection is one of the most important decisions a grower makes for a successful crop.
Pod Drop and Pod Shattering
Preharvest seed loss is one of the greatest threats to yield potential in canola. Two processes are responsible – pod drop and pod shattering. Pod drop occurs when the entire seed pod falls to the ground; pod shattering occurs when the pod remains attached to the plant but splits open, dropping seeds to the ground (Figure 1). Both pod drop and pod shattering are affected by plant genetics and the environment, but pod drop appears to be more affected by environmental conditions.
Figure 1. Pod shattering in canola.
Pod Shatter Resistance: Until recently, swathing was the common practice in canola production largely to ensure uniformity in plant maturity and because earlier canola varieties lacked strong pod integrity, often leading to both pod drop and shattering if left longer in the field. Today, however, pod shatter resistant canola products have changed the picture. Selection through breeding has resulted in products that now provide a level of pod shatter resistance not found in the older varieties and offer growers greater flexibility in their harvest management options. Instead of a single reliance on swathing, growers with pod shatter resistant canola products can opt for straight combining. Straight cutting canola allows the crop to mature longer in the field which can result in more seed production and increased seed size. Products have shown not only to be more resistant to shattering during harvest but are also less impacted by adverse weather before shattering occurs. This trait can help increase yield potential, particularly if delayed desiccation and combining are desired. SC canola products developed by Bayer are well-suited for leaving the canola in the field to maturity for straight cutting. SC+ canola products developed by Bayer strengthen canola pods and have demonstrated increased tolerance to pod shattering compared to products without the trait.
The benefits of shatter resistance can be seen by the rapid adoption of the technology over the last several years. In Manitoba, for example, over 60 percent of canola growers are now using some form of shatter resistance.1
Lodging occurs in canola when plants fall over, making harvest difficult (Figure 2). Canola yields can be reduced by 16 to 50 percent in lodged fields.2 Environmental conditions, agronomic practices, plant genetics and insects and diseases can cause lodging to occur.
Figure 2. Lodging in canola. Photo courtesy of Courtney Meduna, Bayer.
Genetic Improvements to Standability: Key plant characteristics that increase the risk of lodging include stem and tap-root anchorage strength, as well as canopy height and weight. Canola products with strong stems and a tendency to branch in growth rather than to increase height, have reduced the likelihood of lodging. These genetic improvements in standability can help increase both harvest efficiency and yield potential.
Proper harvest timing is critical with canola for maximum yield potential. Late harvest increases the possibility of losses due to pod drop and pod shattering as canola plants mature and dry. Extreme weather events at this time can also increase the risk for pod drop and pod shattering once the plants have dried down. The potential for lodging is also increased as plants continue to mature. In addition to seeding date, plant genetics also plays a large role in maturity at harvest because of the wide variation in days to maturity in canola (Figure 3).
Genetic Improvements to Maturity: Through plant breeding efforts, earlier maturing canola seed products are now available. Switching from a longer maturing product to a shorter season product can offer a gain of 1 to 2 weeks in harvest timing.3 Canola that matures earlier in the fall can help mitigate losses from pod drop, pod shattering, lodging and other stresses from fall frost. Bayer offers a range of product maturity options to meet individual farm needs. This portfolio of products with different maturities can help farmers increase their harvest window and decrease their risk of losses.
Figure 3. Maturity differences in canola. Photo courtesy of Meghan Desjardins, Bayer.
In the case of fields with uneven maturity (Figure 4), the least mature areas of the field should be left to finish out and harvested later than areas of the field that are more mature. Also, swathing can help mitigate risk in fields with uneven maturity. For timing of the swath, the goal is 60 percent seed colour change on the main stem.4 It is advised to wait until the least mature areas show some colour change on the bottom pods and seeds in the outer branches are not translucent or mushy. In fields planted with improved shatter resistance products, it may be possible to delay swathing to let the field become more uniform in maturity. In cases where swathing is not an option, a decision will need to be made to either let the uneven areas mature naturally or apply a pre-harvest product before straight combining.
Figure 4. Uneven maturity in a canola field. Photo courtesy of Courtney Meduna, Bayer.
Points to Keep in Mind
- Even when using products with pod shatter resistance and whether straight combining or swathing, the timing of harvest is still a critical factor in the reduction of potential yield losses from pod drop and pod shattering. Assessing when canola is ready to be harvested and doing so in a timely manner is vital to help protect against pod drop and pod shattering and reduction in yield potential.
- Along with pod shatter resistance, yield potential, days to maturity, standability and herbicide system are important factors in selecting a canola product, particularly with straight combining.
- Because of the strong link between disease and lodging, a good disease resistance package that works for conditions on your farm, along with standability traits, can help reduce lodging and maintain yield potential.
- In addition to earlier maturing canola products, altering seeding rates and dates can change the time to harvest.
- Selecting canola products with different maturities should be considered to help manage harvest timing and reduce risks. Seeding early maturing canola products first and long-season maturing products last can help reduce the risk of harvest losses and help manage the harvest workload on the farm.
For more information on managing your canola harvest, please see Canola Harvest Management. Timing Seeding Date and Maturity for Canola Harvest Management.